In the manufacture of rotary heat regenerators for residential use, it has been found possible to form the regenerator wheel from a spiral wound strip of plastic for reasons of economy, and it has been found unexpectedly that such a wheel will have a heat exchange efficiency greater than that of a wheel made of an expensive metal such as stainless steel.
However in the manufacture of such a matrix utilizing a plastic strip, the strip cannot be wound too tightly since excessive tension during winding will reduce the size of the air passages and reduce the efficiency of the matrix. For this reason such a matrix has little strength, particularly in a direction transverse to the plane of the matrix.
In residential use, the gas passages of the matrix may tend to clog with dust, grease, lint, animal hair, or the like, and therefore it is desirable that the wheel should be easily removed for either cleaning or replacement, and that the portion of the structure that must be removed or replaced comprise as little of the wheel structure as possible, for reasons of economy.
Since two separate blowers are required to form the two separate air streams, and means must be provided for rotation of the matrix wheel, the manufacture of such regenerators has been unduly expensive, limiting their use in residential applications.